You can show your love for KDE in many ways. Here are a few places where you can buy t-shirts, books, mugs and more.
Link: http://kde.slimbook.es/
Link: http://www.cafepress.co.uk/kde
Link: https://www.freewear.org/?org=KDE
Link: https://www.hellotux.com/kde
Link: https://20years.kde.org/book/